Modeling languages have been created to express structure, flow, and other information about software, organizations, and other systems which behave (at least in part) according to a set of rules. Modeling languages may be textual, graphical, or both. Textual modeling languages provide standardized keywords, which may have associated parameters, to represent concepts and relationships. Graphical modeling languages provide design diagrams with named symbols to represent concepts, and lines connecting the symbols to represent relationships between the concepts. Graphical modeling languages are sometimes known as visualized modeling languages, and their named symbols are sometimes known as elements.